Patent Document 1 discloses a communication method in which a polarized-wave multiplexing transmission scheme using an XPIC (a cross polarization interference canceller) and a spatial multiplex transmission scheme using a MIMO (multiple-input multiple-output) system are combined. By using this communication method, the signal multiplicity can be increased, and thus, the capacity of a communication path can be increased. However, when a communication device supporting the communication scheme is actually operated, the stability of communication performed by the polarized-wave multiplexing transmission scheme or the spatial multiplex transmission scheme varies in accordance with the state of the transmission path. Accordingly, stable communication is difficult to secure.
Meanwhile, Patent Document 2 suggests appropriately switching communication schemes in accordance with the state of a transmission path.